Metal coating metal sheets



July. 30, 1929. 5 w ET AL 1,722,949

METAL COATING METAL SHEETS Filed June 1, 1926 mm BY Patented J uly. 30, 1929.

UNITED STATES I 1,722,949 PATENT OFFICE.

EARL R. WEHR AND CARL C. MAHLIE. O15 MIDDLETOWN? OHIO, AND JOHN R. CAIN, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNORS T THE'ANLERICAN ROLLING MILL COMPANY, OF MIDDLETOWN, OHIO, A CORPORATION 01 OHIO.

METAL comma METAL SHEETS.

Application filed June 1,

. capable of being fed through a bath,the invention has more general aspects as will subsequently appear.

In the coating of sheet metal by the method of feeding it through molten metal baths, and particularly with iron and steel, when subjected to surface treatment with metals which coat the iron, the problem of securing a proper coating is rendered difficult because of the large area which must be covered, and because of the distinctness with which any defect appears on the large, smooth, flat area.

It has long been considered a possible ad-.

vantage in the protective coating of sheet mctahparticularly iron and steel, to employ an alloy of zinc and aluminum instead of a zinc spelter. The difiiculties met with in such attempts as have been made in the past to use zinc aluminum instead of spelter in the usual galvanizing process are twofold. In the first place, an attempt to establish a usual flux at the entrance point in the coating bath, will result in the production very rapidly of a thick, gummy product which it is impossible to employ. In the second place, those parts of the bath which are apparently free of the flux, develop an improperly liquified scum, which makes it impractical to get the sheets out of the bath, using known galvanizing practice. I

IVe have developed a process, however, which takes care of these various factors, eliminates the necessity of giving more than one coating treatment, and produces ahighly satisfactory product. We can, for example, produce sheets by the use of a process employing ordinary coating equipment, which product is coated with pure zinc and aluminum alloyed with each other, has no spangles, can withstand all the usual bending requirements, and is practically unaffected by oven heat such as is encountered in domestic stove practice.

We accomplishour objects by that certain process to be hereinafter more specifically pointed out and claimed. a

1926. Serial No. 112,866.

In the drawing the figure is a diagram of equipment found by us to be satisfactory with our process.

having a pot l, with guides 2, feed rolls 3,

exit rolls 4, and flux box 5. The flux box should have the compartment 6 for a heat unit 7, where using pure zinc. The exit rolls have located alongside of them, any desired .stirring devices that are found convenient stirred and: avoids improper surface conditions;

By the term pure zinc, we refer to commercially pure zinc, as distinguished from the ordinary zinc spelter, (prime western), which is'an alloy. Either type of zinc may be used with our process, however.

The level of zinc-aluminum alloy is indicated at 10, and the pure zinc beneath it at 11. The level of the molten zinc is shown at 12, where no alloy ison its surface. The level of flux in the flux box is shown at 13.

' As a flux zinc-aluminum chloride is used, together with ammonium chloride, and if some little aluminum by mischance get into the flux box, it will benecessary-to recondition it by the addition of. hydrochloric acid to the flux box.

The cleaned metal sheet is passed through i the flux into the zinc, where it becomes zinc coated and thence up through the exit end of the bath, as drawn by the exit rolls, where it becomes coated with zinc-aluminum alloy. The amount of aluminum in the floated alloy at the exit end will be maintained at the desired percentage by additions of aluminum from time to time. The agitators will keep the alloy fairly uniform, and-in our practice we keep the alloy at around six per cent aluminum, although this amount is not an essential. We find that an alloy of much less than two per cent of'aluminum on the final product does not give the best results.

l/Ve have shown a galvanizing equipment The final product is not spangled it pure zinc is used, but if ordinary zinc spelter (prime western) be employed, the surface will spangle unless very careful control of the cooling of the sheet is exercised. However, even it the sheet does spangle, bend to a lapped fold (180 degrees) and will withstand oven temperatures without discolwe claim' as new and desire to secure by Letters Patent, is z- I 1. A process of coating ferrous sheets with zinc and aluminum which consists in passing the sheets through a flux and into a molten bath of the zinc and thence up through a molten alloy of zinc and aluminum floating on the surface of the zinc.

2. A process of coating ferrous sheets with zinc and aluminum which consists in passing the sheets through a flux and into a molten bath :of the zinc and thence up through a molten alloy of zinc and aluminum floating on the surface of the zinc, and kept from access to theflux.

A process of coating ferrous sheets with it will zinc and aluminum which consists in passing the sheets through a flux and into a molten bath of the zinc and thence up through a molten alloy of zinc and aluminum floating on the surface of the zinc, and kept from access to the flux and agitating the said alloy.

4. A process of coating ferrous sheets with zinc and aluminum'which consists in passing the sheets through a flux and into a molten bath of the zinc and thence up through a molten alloy of zinc and aluminum floating on the. surface of the zinc, said zinc being pure. i

5. A process of coating ferrous sheets with zinc and aluminum which consists in pass.-

' in" the sheets through a flux and into a molten bath of the zincand thence up through a'molten alloy of zinc and alumir num floating on the surface of the zinc, and kept from access to the flux, said alloy being agitated and said zinc being pure.

G. A process for coating a metal body with alloys containing zinc and aluminum, which consists in passing the body through a molten flux into a molten metal body on which is floating a molten alloy containing zinc and aluminum, preventing the alloy from getting into the flux and agitating the alloy, and passing the article from said metal body out through the floating alloy.

EARL R. WEHR. CARL C. MAHLIE. JOHN R. CAIN. 

